$ { {2} \times \left[\begin{array}{rrr}{-2} & {-1} & {4} \\ {1} & {2} & {1}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rrr}{2}\times{-2} & {2}\times{-1} & {2}\times{4} \\ {2}\times{1} & {2}\times{2} & {2}\times{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{-4} & {-2} & {8} \\ {2} & {4} & {2}\end{array}\right]}$